Discuss about the International Symposium and Euro Conference.
There are many industries in the broader construction industry which require that steel members are welded directly into each other. These include the building industry, road construction, offshore structural construction and many more. These are the places where square hollow section joints have found most of their application (Owen Kelly 2001). Sally, to reduce the difficulty level when cutting and fabricating such structures, welded SHS_SHS connection structures have their chord walls aligned either perpendicular or parallel, or both ways, to the walls with the braces. This is made even easier by the fact that other configurations can be generated by simply rotating either the chord only (square bird-beak joint) or both the chord and the brace (diamond bird-beak joint).
For a long time, the construction industry had been suffering from the effects of having to bend walls to move forces between members. But the discovery and use of bird-beak joints have mitigated this challenge by improving certain mechanical behaviors. How? The new orientations described above allow the joints to transfer forces among the members simply through initiating a natural in_plane action. According to researchers and construction experts, bird-beak joints have higher ultimate strengths than the usual joints even when they are bestowed with similar non-dimensional variables (Owen et al. 2001). Unfortunately, there is still no significant information regarding the behavior of bird-beak joints when under fatigue.
This takes us back a little to DBB joints. The field of civil, structural engineering has, for a long time, used welded truss structures with square hollow sections to reduce stress where fatigue loading may be an irrevocable part of the design. Luckily, there are several types of tubular joints available for varied forms of trusses. Lest we forget, T-joints are a part of DBB joints, for which a lot of research has been ongoing. Based on the opinions of researchers, compared to the conventional SHS joints, DBB joints have shown greater static strength. There is more information concerning the formula design for the static strength of DBB T- and K-joints in the CIDET design guide, episode 3.
However, welded tubular joints, just like the rest that we have so far seen, have flaws t which remedies have not yet been found (Chtistitas 2007). It was found that these kinds of joints bend down to fatigue when cyclic loading is done for a long time due to a high concentration of stress. Accuracy in the methods of design is a primary instrument if one has to achieve a safe and economical design. Recent studies on tubular joints indicate that more research is required, particularly for certain specific geometries which feature failure modes with similar load predictions that are neither safe nor economical. A comprehensive investigation conducted and published in the year 1982 was the first to formulate a numerical model containing shell elements.
Post-yield responses have been seen in several kinds of tubular joints because of the effect of the hardening of strain in the material, and the chord’s membrane forces. So far, many researchers have tried to find the limit of deformation that helps to determine the ultimate joint strength. Experiments can, and have been done, that pitches the brace and chord axial forces against the factors influencing the concentration of stress for square bird-beak T-joints (Lei L 2009). The results and conclusions obtained, if based on the finite element analysis, brings some conclusions that are worth mentioning, as follows;
The conclusions and assumptions highlighted above are just some of the many assumptions mentioned in the aforementioned. The ones listed above here are just but the major ones (Zhu Z & Liu S 2012). When a square bird-beak T-joint is subjected to an out of plane bending, the observations on the factors affecting stress and the behavior of square bird-beak T-joints, an approach that applies quadratic exploration is always used to calculate the hot spot SCFs because of the important non-linearity of distribution of stress within the regions of extrapolation.
That said, it can be seen clearly that these T-joints have been of tremendous help to the construction industry, as well as related industries which may find the application of these joints appropriate. This study was designed to build and study certain simulations that would be used to gain further insight into the two toes of t joints specified herein (Ishida K 1992). And see if solutions can be found to mitigate the problems that have been found to be plaguing them so far.
This project will be designed to come up with simulations that will be used to gain insight into the issues surrounding hollow section tee joints. This will mean that materials will have to be purchased, one of which will be materials that can be used to build the T-joints themselves. Based on the relevant tests that will be carried out, the research group will meet to decide on the material they will use to make the tee joints, and how many tee joints will be needed. The research will be majorly quantitative as it will involve a lot of calculations and numerical explanations. There will have to be electricity and a source of heat that will b used to accomplished tests or experiments that will require the application of high temperatures, like the fire tests.
Other requirements that will be needed will include a vice or a press for experiments that will involve measuring the strengths of the tee joints that will be made. And although the project doesn’t look so big, it may cost a fortune given the nature of the materials we will need to build the tee joints. The estimated cost of buying things like metal pipes, plastic pipes, and other critical accessories is quite high, not to forget that a welding machine will have to be hired (the school welding machine is broken down). Generally, the whole process is estimated to cost around three thousand dollars minus the expenses that will be incurred besides the ones I have just talked about.
The project is scheduled to last no more than three months. Given the financial cost, if it goes more than the speculated three months, a lot of money will have to be spent, which may not be readily available.
The sole method of collection of data will be through observation. Literature regarding the experiments to be carried out will be obtained from notes given in class and those retrieved from the school library, or authorized and trustworthy internet sources. The researchers will visit a few selected buildings and structures to observe the type of joints used with them and record where they thought there was a problem, and where they thought the design was excellent. These will be used to develop more insight into the research question, or problem.
The data analysis methods that will be used will be both quantitative and qualitative data. The quantitative data will be analyzed by use of suitable tools of analysis like graphs and charts. But the qualitative data will have to be merely looked at, checked to see if there are cracks or chinks in the structures of concern. After the research is complete, the researchers will countercheck to see if the research has met the set objectives. The researchers will then make recommendations for best practices that can be used to answer the research question or the best actions that can be applied to mitigate the research problem. The research will end with a written report with detailed documentation of everything I have written in this overview.
The principal objective of the examination was to build up the temperature dispersion in every segment of the association. Amid the tests, the temperatures in specific areas of the joint zone were estimated. The outcomes showed that the joint-zone temperature field fluctuates astoundingly among various joint writes (Lei L 2009). Thus, the joint ought to be partitioned into segments with a similar temperature dispersion. This recommends that the part strategy for figuring the mechanical properties of basic joints at surrounding conditions might be utilized to get the joint temperatures and as a result the conduct of the entire unprotected steel structure. To build up the part strategy, a limited component (FE) display was utilized to mimic the joint conduct under flame conditions. The trial comes about have been utilized to approve and check the numerical model made in Abaqus/CAE programming to build up the proportional part factor for every district of the joint in additionally considers (Lei L 2009). Applying the current design models, it is hard t ascertain exactly the failures mechanisms and modes to be placed under consideration in tabular joint design tests. Very minimal attention has paid to the distinctions between the temperature distribution connecting one set of the joints to another and the effects of these temperature variations in consideration to the failure mode. The study also shows that the component method is another technique used in designing the steel joint.
This method states that the joints are to be decomposed and isolated into various elements basing on the evaluation of the mechanical properties making each element. However, more information is needed to make this method to fire conditions. In this regard, the temperature distribution in the joints is required to be known to carry out more sophisticated calculation models, which will consider the e3ffects of the structure and the increase of the internal forces (Lei L 2009). This project will be designed to come up with simulations that will be used to gain insight into the issues surrounding hollow section tee joints. This will mean that materials will have to be purchased, one of which will be materials that can be used to build the T-joints themselves. Based on the relevant tests that will be carried out, the research group will meet to decide on the material they will use to make the tee joints, and how many tee joints will be needed. The research will be majorly quantitative as it will involve a lot of calculations and numerical explanations. There will have to be electricity and a source of heat that will b used to accomplished tests or experiments that will require the application of high temperatures, like the fire tests. This experiment of the fire test concerning the temperature distribution has been carried out over and over again by various research institutions like the University of Manchester. And in their research studies, they concentrate on the temperature change about the individual elements of the reverse channel section made to focus tabular columns. Therefore, the biggest concern here is present uniformity of measured temperature with the temperature time frame gotten in accordance with current structural designs of the T-joints.
According to Peter and Gregory (2006), the authors of the article on the theoretical or conceptual investigation of the Column Behavior of the Cold-Formed Square Hollow Sections, an experiment which was undertaken at the University of Sydney with regards to the Australian manufactured cold-formed square hollow sections. The experimentation was largely based on the stub and pin-ended column and the varied measurements of the yield stress and the consequential residual stress initiated around the section. It also showed various deflection elastic-plastic finite strip evaluations incorporating measured distributions regarding the yield stress and the residual stress of the stub and pin-ended column. More specifically, the impacts of the measured thickness residual stress elements were shown. Furthermore, the analysis of accounts regarding the plate geometric imperfections, the varied degree of the yield stress revolving a section, the attributes of the stress-strain of the materials making this particular section and the highly dynamic or complex patterns with regards to the residual stress produced in the process were also demonstrated (Owen et al. 2001). And finally, the relationship between the outcome of the analytical frame concerning the test experimented was also demonstrated.
In the contemporary world, the research studies have it that, testing and finite element modeling of the square hollow section and bird-beak T-joints is the story of the day. Particularly, the cold-formed steel hollow sections have gained an increasing application in various structural and mechanical industries. In this study, it was realized that the cold-forming process for hollow sections might not necessarily incorporate post forming stress relief, thereby, being a dynamic distribution of the yield stress around the section. Also, for some specific parts which are not free from the stress, the increased gradients of the residual stress via the plate thickness are bound to contain a profound influence on a section compression mechanisms and behavior (Owen et al. 2001). Similarly, the various experiments and analytical studies have been put forward on the impact of the high through-thickness on either sections or the column behavior. Therefore, it is very fundamental for this particular section of the study to investigate the load-deformation behavior of the Hollow Sections T- Joints with regards to testing and finite element modeling of the square hollow section and bird-beak T-joints conceptually. This should put into consideration, the entire instability, material yielding and the requirements of the hollow section T-joints and the geometric imperfection (Owen et al. 2001). A conceptual or theoretical elastic-plastic huge displacement analysis with regards to the finite strip technique of analysis of thin-walled sections was established. This finite evaluation or analysis can be responsible for huge displacements, elasticity and the original conditions of geometric imperfection. Studies also showed that the analytical load deformation outcome of this particular square hollow section columns concerning the finite strip analysis could be compared to the experimental mechanisms for either the stub columns or the pin-shaped columns. The analytical framework of the dynamical parts of the residual stress and yield stress can quantify as experimental program parts and is incorporated in the finite analysis as postulated in this section.
Various researchers and scholars in countries like Japan have initiated and developed profound experimental and conceptualized investigations into the attributes and behavior of Hollow Sections T- Joints. Kato and Nishiyama applied linear regression analysis of the experimental outcomes to outline trends, properties, and behavior of the Hollow Sections T- Joints. In their research findings, they summarized that apparently, there are no other elaborate studies available in the literature with regards to the local buckling attributes of this particular machine. A global summit on safety technique in the modeling of steel structures held in Tokyo Japan around the year 1986 outlined a remarkable amount of research study undertakings at that very moment. Kato and the fellow researchers examined the impacts of the cold-forming residual stresses together with the influence of circular corners on the square hollow section behavior. By extension rigorous analytical models, for instance, the displacement plasticity finite component analyses, the analysis of the response to the longer pin ended columns is far much beyond the digital resources available to various structural researchers, particularly in the contemporary society. Hypothesis, have therefore been created which utilize simplified frameworks of cross-section behavior as the foundation of the huge displacement analysis of the entire frame (Chtistitas 2007). For example, according to Davison and Birkemoe, two concepts or the theoretical pin-ended column have been developed, one based on the tangent modulus theory and the other one on the theory of the maximum strength. Although, in this experimentation, many results were calculated or computed using the theory of maximum strength, with regards to the recent developments and trends in column design. Ultimately, it was realized that the finish parts of the residual stress were comparatively minimal; however, the effects of either yield or residual stress were put under consideration.
The finite analysis strip process in which the prismatic element of the group is discretised into various strips is simply considered to be a modification or development in the more generalized finite process. Though the finite element process or technique applies polynomial displacement functions in either direction, on the other hand, the finite strip process applies a continuously differentiable smooth sequence in the longitudinal direction and a comparably simple polynomial function its transverse direction. The compatibility between the strips I offered through the transverse polynomial functions whilst the longitudinal functions applies satisfaction at the end of the boundary conditions (Chtistitas 2007). Therefore, the following assumptions can be made from the present finite strip formulation;
Research studies still show that the entire buckling displacement functions applied in the finite stripe analysis are used to model the overall buckling behavior of the square hollow section and bird-beak T-joints. Otherwise, the finite strip section discretization used for the pin ended column generally contains six similar width strips with two narrow strips in every corner modeling its properties. Both the residual stress and the yield stress variation around the sections are made in a similar manner to form stub columns.
According to Lewei Tong et al. They suggest in the Journal of Construction Steel Research that fatigue tests and modeling or design of diamond bird-beak SHS T-joints and axial loading in brace and chord members both revolve or rotate at forty-five degrees. For this particular study, welded truss structures manufactured of square hollow sections (SHS) have been used widely in civil structural engineering where heavy loading may take over the entire design. Probably various forms of tabular joints are very useful for various forms of trusses. Bird-beak joint in this regard has taken the lead of being the best choice simply because of its outstanding remarkable appearance and the best structural behavior shown by recent research studies. This particular design is made out of the convention SHS T-joint by rotating both of its chord and brace members through an angle of forty five degrees. There are only two specifications of configurations in this particular one, square bird-beak T-joint with particularly double chords moving at forty five degrees and what is known as diamond bird-beak T-joint with the entire brace and chords moving at angle of forty five degrees. In this study otherwise, the former has been accorded priority. Ideally, extensive studies have been done concerning on the static performance of this particular T-joint. According to the researchers, the DBB T-joint has demonstrated a huge static strength in comparison to the SHS joints (Chtistitas 2007). Also the design formulae for its static strength are available in various design guides. The research also shows that the welded tabular joints are susceptible to fatigue failure when subjected to a long-term cyclic loading maybe because of high concentration. However, in regard to the DBB joints there are confirmation statements that limited research has been undertaken regarding its fatigue failure. According to Ishida et al. in DBB there is probably greater fatigue strength in comparison to the conventional T-joints. Generally, for the DBB joints put under axial loading in the brace, crack points can be initially observed at the welded toes at the saddle in the chords. The crack grew lengthwise in the direction of the chord crown at a certain degree. Further, the cracks that come lately at the chord crown intensified in the direction nearly ninety degrees to the axis of the chord. This typically happen the fatigue strength of the DBB joins are tested or subjected to a cyclic axial loading in the brace.
According to Jolanta et al. in the same journal of Constructional Steel Research with regards to experimental and the numerical examination on the temperature distribution of square hollow section joints, their study gives an assertion to the experimental and numerical outcome concerning temperature distribution of the unsecured square hollow section SHS joint in a standardized fire test. The experiment program can be done or constructed using threes fire test upon which six joints with varied configurations and different brace measurement are tested. Otherwise, the main aim of doing this was to establish the temperature distribution in each T-joint examined (Chtistitas 2007).
According to the research study, the vital section of the tubular steel structure is the joint connection between the brace and the chord members. The behavior of the tubular joint is structured at room temperature, but there has been limited research describing the experiments under such conditions. Applying the current design models, it is hard t ascertain exactly the failures mechanisms and modes to be placed under consideration in tabular joint design tests. Very minimal attention has paid to the distinctions between the temperature distribution connecting one set of the joints to another and the effects of these temperature variations in consideration to the failure mode. The study also shows that the component method is another technique used in designing the steel joint. This method states that the joints are to be decomposed and isolated into various elements basing on the evaluation of the mechanical properties making each element. However, more information is needed to make this method to fire conditions. In this regard, the temperature distribution in the joints is required to be known to carry out more sophisticated calculation models, which will consider the e3ffects of the structure and the increase of the internal forces (Chtistitas 2007). This experiment of the fire test concerning the temperature distribution has been carried out over and over again by various research institutions like the University of Manchester. And in their research studies, they concentrate on the temperature change about the individual elements of the reverse channel section made to focus tabular columns. Therefore, the biggest concern here is present uniformity of measured temperature with the temperature time frame gotten in accordance with current structural designs of the T-joints. For the better visibility of the variables, the factors or measurement with the same temperature and time are recorded or included from the analysis to avoid the obvious errors and mistakes.
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